For example, known as a valve device that operates under a high-pressure condition is a device including: a main valve element that blocks and opens a main passage formed at a housing; and a pilot valve element that controls opening/closing operations of the main valve element. For example, PTL 1 discloses a valve device in which a main valve element and a pilot valve element are arranged coaxially.
FIG. 10 shows a part of a valve device 100 disclosed in PTL 1. A primary passage 121, a pressure chamber 122, and a secondary passage 123 are formed at a housing 110 of the valve device 100. The primary passage 121, the pressure chamber 122, and the secondary passage 123 constitute a main passage 120. The secondary passage 123 is opened and closed by a main valve element 140. A pilot chamber 130 is formed on an opposite side of the pressure chamber 122 across the main valve element 140. The pilot chamber 130 communicates with the pressure chamber 122 through a first pilot passage 131 that is a gap between the main valve element 140 and the housing 110. A second pilot passage 132 is formed at the main valve element 140 and is opened and closed by a pilot valve element 150. The pilot valve element 150 is driven by a solenoid (not shown).
Further, in the valve device 100, the main valve element 140 and the pilot valve element 150 are coupled to each other by a pin 160. The pin 160 is fitted in a transverse hole of the pilot valve element 150 without any gap. However, a gap is formed between the pin 160 and a support hole 141 of the main valve element 140, and therefore, the pilot valve element 150 can be separated from the main valve element 140 by the gap.
The pilot valve element 150 is pressed against the main valve element 140 by a spring (not shown). When a current flows through the solenoid (not shown), the pilot valve element 150 is first separated from the main valve element 140 by the gap between the support hole 141 and the pin 160. Thus, the second pilot passage 132 is opened. Then, when differential pressure between the pilot chamber 130 and the secondary passage 123 becomes low, and attractive force of the solenoid attracting the pilot valve element 150 exceeds biasing force of the spring biasing the pilot valve element 150 and pressure of the pilot chamber 130, the main valve element 140 is pulled upward. Thus, the secondary passage 123 is opened.